The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

Rods

Opponent-process theory

The theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulate by green and inhibited by red; others are stimulated by red and inhibited by green

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Fovea

The central focal point in the retina, around which the eye's cones cluster

Perceptual constancy

Monocular cues

Depth cues, such as interposition and linear perspective, available to either eye alone

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Transduction

Conversion of one form of energy into another. Ex: sights, sounds, and smell change into neural impulses our brain can interpret

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Weber's law

The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

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Binocular cues

Depth cues, such as retinal disparity, that depend on the use of two eyes

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Place theory

In hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated

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Retinal disparity

A binocular cue for perceiving depth: by comparing images from the retinas in the two eyes, the brain computes distance-the grater the disparity (difference) between the two images, the closer the object

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Pitch

A tone's experienced highness or lowness; depends on frequency

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Bottom-up processing

Analysis that begins with the sensory receptors and works up to the brain's integration of sensory information

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Feature detectors

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

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Gate-control theory

The theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signaled traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain

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Psychophysics

The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them

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Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation

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Signal detection theory

A theory prediction how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivations, and alertness

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Top-down processing

Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experiences and expectations.

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Accommodation (perceptual)

The process by which the eye's lens changes shape to focus near or far objects on the retina

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Frequency theory

The theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

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Habituation

Decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their wanes and they look away sooner

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Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina

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Optic nerve

The nerve that carries neural impulses from the eye to the brain

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Pupil

The adjustable opening in the center of the eye through which light enters

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Vestibular sense

The sense of body movement and position, including the sense of balance

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Blind spot

The point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

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Iris

A ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

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Hue

The dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth

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Sensation

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment